cool radiators

DM_2

I had a new burnham gas fired boiler installed for my one-pipe steam system 6 months ago and just have a couple questions:
I have a trouble getting the radiators hot at the end of my first 45' main (no main vents and the other 25' main heats fine) is there anyway to get them hot without installing main vents? I have the pressure set to approx 1psi on the diff scale and approx 1.5psi on the main which I believe would give me a .5 cut-in (subtractive) . It's a honeywell L404A and it only goes down to 2psi on both scales so I'm estimating those #'s.
I have to set my anticipator to 1.2 to get them at least warm but I would rather lower it to have it cycle more often, but that leaves them cold. Any suggestions?
My other problem is that when the old boiler(original) was removed the amount of sludge was amazing it looked as though it had not been cleaned in 20 years. I have had to flushout my boiler more than I would like, I know fresh water is not good but there has been so much sludge coming down from the rads and pipes it starts banging after about a month. Can I clean some piping this spring by removing some of the rads and sticking a hose down the valve and try to push some of the sludge(from the pipes that go from the main to the rad, some aren't pitched well) into the boiler?
Also is the best time to flushout a boiler right after it has gone through a cycle and is still hot with a little pressure in the system?
P.S. All new Gortons vents.
Sorry about the long post.
Thanks in advance, any help appreciated
DM